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| ASME Y14.5 - Dimensioning and Tolerancing | Reference | 2018 |
| The actual value of any individual distance at any cross section of a feature of size. |
| A similar perfect feature(s) counterpart of smallest size that can be contracted about an external feature(s) or of largest size that can be expanded within an internal feature(s) so that it coincides with the surface(s) at the highest points. This envelope is on or outside the material. There are two types of AMEs, as described below. (a) related AME: a similar perfect feature(s) counterpart expanded within an internal feature(s) or contracted about an external feature(s) while constrained in orientation, in location, or in both orientation and location to the applicable datum(s). (b) unrelated AME: a similar perfectfeature(s) counterpart expanded within an internal feature(s) or contracted about an external feature(s), and not constrained to any datum(s). |
| A similar perfect feature(s) counterpart of largest size that can be expanded within an external feature(s) or of smallest size that can be contracted about an internal feature(s) so that it coincides with the surface(s) at the lowest points. This envelope is on or within the material. There are two types of actual minimum material envelopes, as described below. (a) related actual minimum material envelope: a similar perfect feature(s) counterpart contracted about an internal feature(s) or expanded within an external feature(s) while constrained in orientation, in location, or in both orientation and location to the applicable datum(s). (b) unrelated actual minimum material envelope: a similar perfect feature(s) counterpart contracted about an internal feature(s) or expanded within an external feature(s), and not constrained to any datum reference frame. |
| The condition of a line element, surface, center plane of feature, tangent plane, or feature axis at an implied or specified basic angle of any value from one or more datum planes or datum axes. |
| The average of several diametric measurements across a circular or cylindrical feature. |
| A tolerance in which variation is permitted in both directions from the specified dimension or true profile. |
| The center plane of the unrelated AME of a feature. |
| The condition in which each circular element of a surface is at zero variation relative to a datum axis or axis of rotation established from the datum reference frame. |
| The condition of a surface in which (a) for a feature other than a sphere, all points of each circumferential line created by the surface intersected by any plane perpendicular to the axis or spine (curved line) are equidistant from that axis or spine. (b) for a sphere, all points of the surface intersected by any plane passing through a common center are equidistant from that center. |
| The condition in which the axis of the unrelated actual mating envelope (AME) or axis of the unrelated minimum material envelope, as applicable, of one or more surfaces of revolution is coincident with a datum axis or another feature axis. |
| A single surface of compound curvature or a collection of features. |
| Two or more interrupted features designated with a CF symbol, indicating they are to be considered as a single feature. |
| Two or more regular features of size or an interrupted regular feature of size that is designated with a CF symbol, indicating they are to be considered as a single regular feature of size. |
| The condition of two or more surfaces having all elements in one plane. |
| The condition of a surface of revolution in which all points of the surface are equidistant from a common axis. |
| A theoretically exact point, axis, line, plane, or combination thereof derived from the true geometric counterpart. |
| The center plane of a true geometric counterpart. |
| The physical boundary used to establish a simulated datum from a specified datum feature. NOTE: For example, a gage, a fixture element, and digital data (such as machine tables, surface plates, a mandrel, or a mathematical simulation) are not true planes, but are of sufficient quality that the planes derived from them are used to establish simulated datums. Datum feature simulators are used as the physical embodiment of the true geometric counterparts during manufacturing and inspection. See ASME Y14.43. |
| The symbolic means of indicating a datum feature consists of an uppercase letter enclosed in a square or rectangular frame and a leader line extending from the frame to the feature, terminating with a triangle. |
| Three mutually perpendicular datum planes and three mutually perpendicular axes at the intersections of those planes. |
| The designated points, lines, or areas that are used in establishing a datum. |
| The symbolic means of indicating a datum target shall be a circle divided horizontally into halves. |  |
| An imperfect (abstract) line formed by the center points of all cross sections of the feature. These cross sections are normal (perpendicular) to the axis of the unrelated AME. |
| An imperfect (abstract) plane formed by the center points of all line segments bounded by the feature. These line segments are normal (perpendicular) to the center plane of the unrelated AME. |
| A numerical value(s) or mathematical expression in appropriate units of measure used to define the shape, size, orientation, or location of a part feature or between part features. |
| A dimension with an associated plus/minus tolerance or limit dimension values. NOTE: Where a plus/minus general tolerance is applied to a dimension, the dimension is considered a directly toleranced dimension. |
| A tolerance in which variation is permitted equally in both directions from the specified dimension or true profile. |
| A physical portion of a part (such as a surface, pin outside diameter, hole, or slot) or its representation on drawings, models, or digital data files. |
| A rectangle divided into compartments containing the geometric characteristic symbol followed by the tolerance value or description, modifiers, and any applicable datum feature references. |
| A general term that is used in ASME Y14.5 Standard to refer to instances in which both a regular and an irregular feature of size apply. |
| The tolerance zone framework that controls the basic relationship between the features in a pattern with that framework constrained in rotational degrees of freedom relative to any referenced datum features. |
| The condition of a surface or derived median plane having all elements in one plane. |
| The condition in which no externally introduced forces other than gravity are applied to a part. |
| Geometric Tolerance | GT, GeoTol |
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| A tolerance indicated using a geometric characteristic symbol. |
| A worst-case boundary generated by the collective effects of the smallest feature of size (MMC for an internal feature of size, LMC for an external feature of size) and the applicable geometric tolerance. |
| A gap or gaps in a feature that divide it into two or more features (e.g., a slot or a groove). |
| There are two types of irregular features of size, as follows: (a) a directly toleranced feature or collection of features that may contain or be contained by an unrelated AME that is a sphere, cylinder, or pair of parallel planes. (b) a directly toleranced feature or collection of features that may contain or be contained by an unrelated AME other than a sphere, cylinder, or pair of parallel planes. |
| The worst-case boundary that exists on or inside the material of a feature(s) and is defined by the combined effects of size and geometric tolerances. |
| The condition in which a feature of size contains the least amount of material within the stated limits of size, e.g., maximum hole diameter or minimum shaft diameter. |
| The worst-case boundary that exists on or outside the material of a feature(s) and is defined by the combined effects of size and geometric tolerances. |
| The condition in which a feature of size contains the maximum amount of material within the stated limits of size, e.g., minimum hole diameter or maximum shaft diameter. |
| The designation used for purposes of general identification. (USAS B4.1) |
| An MMB and an LMB, where at least one boundary is a specified shape that is not a uniform offset from true profile. |
| A worst-case boundary generated by the collective effects of the largest feature of size (LMC for an internal feature of size, MMC for an external feature of size) and the applicable geometric tolerance. |
| The condition of a line element, surface, tangent plane, center plane of feature, or feature axis at an implied or specified basic 0° (parallel) angle relative to one or more datum planes or datum axes. |
| Two or more features to which a position or profile geometric tolerance is applied and that are grouped by one of the following methods: nX, n COAXIAL HOLES, ALL AROUND, ALL OVER, between A and B (A ? B), from A to B (A ? B), n SURFACES, simultaneous requirements, or INDICATED, where n in these examples represents a number. |
| The tolerance zone framework that controls the basic relationship between the features in a pattern with that framework constrained in translational and rotational degrees of freedom relative to the referenced datum features. |
| The condition of a line element, surface, tangent plane, center plane of feature, or feature axis at an implied or specified basic 90° (perpendicular) angle relative to one or more datum planes or datum axes. |
| The location of one or more features of size relative to one another or to one or more datums. |
| An outline of a surface, a shape made up of one or more features, or a two-dimensional element of one or more features. |
| Dimensional information, usually without a tolerance, that is used for reference purposes only. A reference dimension is a repeat of a dimension or is derived from other values shown on the drawing or on related drawings. It is considered auxiliary information and does not govern production or inspection operations. Where a basic dimension is repeated on a drawing, it is not identified as reference. |
| A condition in which a geometric tolerance applies at any increment of size of the unrelated AME of the feature of size. |
| A condition in which a movable or variable true geometric counterpart progresses from MMB toward LMB until it makes maximum allowable contact with the extremities of a datum feature(s) to establish a datum. |
| One cylindrical surface, a spherical surface, a circular element, or a set of two opposed parallel line elements or opposed parallel surfaces associated with a single directly toleranced dimension. |
| The condition in which externally induced forces in addition to gravity are applied to a part. |
| The single worst-case boundary generated by the collective effects of a feature of size’s specified MMC or LMC, the geometric tolerance for that material condition, the size tolerance, and the additional geometric tolerance derived from the feature’s departure from its specified material condition. |
| A general term that applies to both circular runout and total runout. |
| A point, axis, line, or plane (or combination thereof) derived from a datum feature simulator. |
| The condition in which two or more geometric tolerances apply as a single pattern or part requirement. |
| The assigning of tolerances to related components of an assembly on the basis of sound statistics (e.g., the assembly tolerance is equal to the square root of the sum of the squares of the individual tolerances). |
| The condition in which an element of a surface, or a derived median line, is a straight line. |
| A plane that contacts the high point or points of the specified surface. |
| The total amount a dimension or feature is permitted to vary. The tolerance is the difference between the maximum and minimum limits. |
| The condition in which all elements of a surface or tangent plane are at zero variation relative to a datum axis or axis of rotation established from the datum reference frame. |
| The theoretically perfect boundary used to establish a datum from a specified datum feature. NOTE: This term is only applicable to datums. |
| The theoretically exact location of a feature of size, as established by basic dimensions. |
| The profile defined by basic radii, basic angular dimensions, basic coordinate dimensions, basic dimension of size, undimensioned drawings, formulas, or mathematical data, including design models. |
| A tolerance in which variation is permitted equally in both directions from the specified dimension or true profile. |
| A constant distance between two boundaries equally or unequally disposed about the true profile or entirely disposed on one side of the true profile. |
| A tolerance in which variation is permitted in one direction from the specified dimension or true profile. |
| A constant boundary generated by the collective effects of a considered feature of sizes specified MMC or LMC and the geometric tolerance for that material condition. |
